//#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>

void modify(int* &p, int* &q)
{
	p = q;
}

int main() {
	int* p = NULL;
	int i = 10;
	int* q = &i;
	modify(p, q);
	printf("after *p=%d\n", *p);
	return 0;
}